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Sabella E, Moretti S, Gärtner H, Luvisi A, De Bellis L, Vergine M, Saurer M, Cherubini P. Increase in ring width, vessel number and δ18O in olive trees infected with Xylella fastidiosa. TREE PHYSIOLOGY 2020; 40:1583-1594. [PMID: 32705131 DOI: 10.1093/treephys/tpaa095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Xylella fastidiosa (Xf) Wells, Raju et al., 1986 is a bacterium that causes plant diseases in the Americas. In Europe, it was first detected on the Salento Peninsula (Italy), where it was found to be associated with the olive quick decline syndrome. Here, we present the results of the first tree-ring study of infected and uninfected olive trees (Olea europaea L.) of two different cultivars, one resistant and one susceptible, to establish the effects induced by the spread of the pathogen inside the tree. Changes in wood anatomical characteristics, such as an increase in the number of vessels and in ring width, were observed in the infected plants of both the cultivars Cellina di Nardò (susceptible to Xf infection) and Leccino (resistant to Xf infection). Thus, whether infection affects the mortality of the tree or not, the tree shows a reaction to it. The presence of occlusions was detected in the wood of both 4-year-old branches and the tree stem core. As expected, the percentage of occluded vessels in the Xf-susceptible cultivar Cellina di Nardò was significantly higher than in the Xf-resistant cultivar Leccino. The δ 18O of the 4-year-old branches was significantly higher in infected trees of both cultivars than in noninfected trees, while no variations in δ 13C were observed. This suggests a reduction in leaf transpiration rates during infection and seems to be related to the occlusions observed in rings of the 4-year-old branches. Such occlusions can determine effects at leaf level that could influence stomatal activity. On the other hand, the significant increase in the number of vessels in infected trees could be related to the tree's attempt to enhance water conductivity in response to the pathogen-induced vessel occlusions.
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Affiliation(s)
- Erika Sabella
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, Lecce, 73100, Italy
| | - Samuele Moretti
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
- Laboratoire Vigne, Biotechnologies et Environnement (LVBE, EA 3991), Université de Haute-Alsace, 33 rue de Herrlisheim, 68008 Colmar Cedex, France
| | - Holger Gärtner
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Andrea Luvisi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, Lecce, 73100, Italy
| | - Luigi De Bellis
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, Lecce, 73100, Italy
| | - Marzia Vergine
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, Lecce, 73100, Italy
| | - Matthias Saurer
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Paolo Cherubini
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
- Department of Forest and Conservation Sciences, University of British Columbia, 3041 - 2424 Main Mall, Vancouver, BC, Canada
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Santilli E, Riolo M, La Spada F, Pane A, Cacciola SO. First Report of Root Rot Caused by Phytophthora bilorbang on Olea europaea in Italy. PLANTS (BASEL, SWITZERLAND) 2020; 9:E826. [PMID: 32630077 PMCID: PMC7411771 DOI: 10.3390/plants9070826] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/27/2020] [Accepted: 06/27/2020] [Indexed: 11/22/2022]
Abstract
Leaf chlorosis, severe defoliation and wilt associated with root rot were observed on mature olive trees cv. Nera di Gonnos in an experimental orchard at Mirto Crosia (Calabria, southern Italy). An oomycete was consistently isolated from rotten roots of symptomatic olive trees. It was identified as Phytophthora bilorbang by morphological characters and sequencing of Internal Transcribed Spacer (ITS) regions of ribosomal DNA (rDNA). Pathogenicity was verified by inoculating potted two-month-old rooted cuttings of Olea europaea var. Nera di Gonnos in a soil infestation trial. P. bilorbang was re-isolated from roots of symptomatic, artificially inoculated olive cuttings to fulfill Koch's postulates. This is the first report of P. bilorbang on O. europaea L. and on a species of the Oleaceae family worldwide.
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Affiliation(s)
- Elena Santilli
- Council for Agricultural Research and Agricultural Economy Analysis, Research Centre for Olive, Citrus and Tree Fruit-Rende CS (CREA-OFA), 87036 Rende, Italy
| | - Mario Riolo
- Council for Agricultural Research and Agricultural Economy Analysis, Research Centre for Olive, Citrus and Tree Fruit-Rende CS (CREA-OFA), 87036 Rende, Italy
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy
- Department of Agricultural Science, Mediterranean University of Reggio Calabria, 89122 Reggio Calabria, Italy
| | - Federico La Spada
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy
| | - Antonella Pane
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy
| | - Santa Olga Cacciola
- Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy
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Sabella E, Aprile A, Genga A, Siciliano T, Nutricati E, Nicolì F, Vergine M, Negro C, De Bellis L, Luvisi A. Xylem cavitation susceptibility and refilling mechanisms in olive trees infected by Xylella fastidiosa. Sci Rep 2019; 9:9602. [PMID: 31270378 PMCID: PMC6610111 DOI: 10.1038/s41598-019-46092-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 06/19/2019] [Indexed: 01/09/2023] Open
Abstract
In olive trees, Xylella fastidiosa colonizes xylem vessels and compromises water transport causing the olive quick decline syndrome (OQDS). The loss of hydraulic conductivity could be attributed to vessel occlusions induced both by the bacteria biofilm and by plant responses (tyloses, gums, etc.) that could trigger embolism. The ability of the infected plants to detect embolism and to respond, by activating mechanisms to restore the hydraulic conductivity, can influence the severity of the disease symptomatology. In order to investigate these mechanisms in the X. fastidiosa-resistant olive cultivar Leccino and in the susceptible Cellina di Nardò, sections of healthy olive stems were analysed by laser scanning microscope to calculate the cavitation vulnerability index. Findings indicated that the cultivar Leccino seems to be constitutively less susceptible to cavitation than the susceptible one. Among the vascular refilling mechanisms, starch hydrolysis is a well-known strategy to refill xylem vessels that suffered cavitation and it is characterized by a dense accumulation of starch grains in the xylem parenchima; SEM-EDX analysis of stem cross-sections of infected plants revealed an aggregation of starch grains in the Leccino xylem vessels. These observations could indicate that this cultivar, as well as being anatomically less susceptible to cavitation, it also could be able to activate more efficient refilling mechanisms, restoring vessel's hydraulic conductivity. In order to verify this hypothesis, we analysed the expression levels of some genes belonging to families involved in embolism sensing and refilling mechanisms: aquaporins, sucrose transporters, carbohydrate metabolism and enzymes related to starch breakdown, alpha and beta-amylase. The obtained genes expression patterns suggested that the infected plants of the cultivar Leccino strongly modulates the genes involved in embolism sensing and refilling.
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Affiliation(s)
- Erika Sabella
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Alessio Aprile
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy.
| | - Alessandra Genga
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Tiziana Siciliano
- Department of Physic and Math, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Eliana Nutricati
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Francesca Nicolì
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Marzia Vergine
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Carmine Negro
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Luigi De Bellis
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
| | - Andrea Luvisi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy
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Sabella E, Luvisi A, Aprile A, Negro C, Vergine M, Nicolì F, Miceli A, De Bellis L. Xylella fastidiosa induces differential expression of lignification related-genes and lignin accumulation in tolerant olive trees cv. Leccino. JOURNAL OF PLANT PHYSIOLOGY 2018; 220:60-68. [PMID: 29149645 DOI: 10.1016/j.jplph.2017.10.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/25/2017] [Accepted: 10/27/2017] [Indexed: 05/04/2023]
Abstract
Recently, Xylella fastidiosa was reported in Italy, associated with the "Olive Quick Decline Syndrome". The cv. Leccino exhibits an evident tolerance with a slow disease progression compared with the other cultivars. Between the mechanisms proposed to explain the putative tolerance of some hosts to X. fastidiosa diseases, lignin deposition plays an important role. Analysis of phenolic compounds in healthy and infected Leccino and Cellina di Nardò leaves showed, in the two cultivars, a reduction of hydroxytyrosol glucoside (usually associated with drought and cold stress) and, only in Leccino, an increase of quinic acid, precursor of lignin. To determine if lignin biosynthesis is involved in defence response, we investigated the expression of genes coding for entry-point enzymes in different branches of the phenylpropanoid pathway. In stems of Cellina di Nardò infected plants, Cinnamate-4-Hydroxylase (C4H) and 4-Coumarate:CoA Ligase (4CL) resulted strongly down-regulated, indicating a plant disease response since the inhibition of C4H is reported to promote the accumulation of benzoic acid and salicylic acid as defence signals. Instead, in the cv. Leccino, Cinnamoyl-CoA Reductase (CCR, reported to be strongly induced during the formation of lignin defence response associated) was up-regulated in the stem of infected plants; moreover, Polyphenol oxidase (PPO), coding for an enzyme involved in the hydroxytyrosol biosynthesis, was down-regulated. The quantification of lignin in healthy and infected branches of both cultivars, showed a significant increase of total lignin in infected Leccino compared with the sensitive cultivar; moreover, histochemical observations of stem sections exhibited a different lignin distribution in the sclerenchyma and in the xylem tissue of infected Leccino plants compared to sections of healthy ones. Results suggest a critical role for lignin in X. fastidiosa tolerance of cv. Leccino.
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Affiliation(s)
- Erika Sabella
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Andrea Luvisi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy.
| | - Alessio Aprile
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Carmine Negro
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Marzia Vergine
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Francesca Nicolì
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Antonio Miceli
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
| | - Luigi De Bellis
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy
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